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I'm a little surprised at Chef's post above since I was unaware that any ablative was made in black - I know Micron Extra isn't.

Yes Micron Extra, CSC and ACT are all made in Black. The West Marine product number for Micron Extra in black gallons is 1146786.

West Marine PCA Gold also comes in black as does Pettit Ultima SR..

04-01-2009 10:20 PM

T37Chef

I think is was Pettit Trinidad

04-01-2009 10:16 PM

harbin2

Maine Sail
Like I said, I'm not here to debate - I'm here to learn and share. Almost all of what you say makes good sense - wish I had your advice before ordering the Bottomkote (classic). Also, I do appreciate your detailed response. I have been sailing for 45 years but I have only been working on boat bottoms for 5 months. Looks like I'll be looking for something to do with an unopened gallon of Bottomkote. Maybe I can talk a local merchant into taking it of my hands in exchange for a can of red Micron Extra (and the difference in price). In my defense, I DID do an enormous amount of reading - here and elsewhere and I'm normally very skeptical of what I read in forums. I'm a little surprised at Chef's post above since I was unaware that any ablative was made in black - I know Micron Extra isn't.
Brak - please forgive me for the diversion away from your topic.
Thanks again to all.

04-01-2009 08:49 PM

T37Chef

yes, I thought the same thing, fortunately I had only about 10 osmotic blisters about the size of a quarter, and they were not oozing very much

It could have been worse.

04-01-2009 08:32 PM

sailingdog

Those may not be osmotic blisters, but gel coat voids, where there was some contamination between the gelcoat and the first layer of matte. That's certainly what they look like. Osmotic blisters would be weeping.

Most hard paints are ineffective after a haul out. No matter how much you want them to work they are toast. If the paint becomes ineffective due to time in water or a haul out what is the point of having a hard paint under an ablative. It will be as effective as the barrier coat after the first season. It is a total waste of time if you are thinking it will offer any protection if your ablative layers wash away.

In a recent post on a similar topic I said I would consider using a hard paint for the first coat...may I retract that statement? When I did my bottom repair I used only ablatives, and now I am glad I did because what MS states makes total sense.

Below shows two coats of black ablative over the barrier coat, followed by one coat of blue ablative:

For the record, I spent the better part of a day sanding my hull using many 60 grit sanding disks after the blasting job was done. Maybe he didn't do as good as job as he should have blasting the hull? Maybe it was because there was years of hard paint build up, the boat is a 1982?

Dunno know, but the blasting did take off most of it (99%) and there was a lot to remove. I wanted to be sure, so I sanded till all I saw was pure white gel coat. So, three years now with the boat being stored in the water year round and I have found zero signs of blistering, voids, etc.

Here is what it looked like after he was done (yes, those a hundreds of tiny blisters about the size of a baby pea):

04-01-2009 06:44 PM

sailingdog

Yeah, that's about as likely as the Cubs winning the World Series in a reverse sweep against the Yankees.

True, but you haven't sodablasted the hull, so the damage might actually be centered around the two fastener holes.... What is immediately visible is the shape of the block. Also, if the outer layer is matte, which is usually the case, the different directions could be due to the water wicking along the CSM strands.

I have cleaned paint off around the area and verified that gelcoat is in just as good a condition as elsewhere immediately outside the ground plate area. It really is a perfect straight line demarcating the damage and the good gelcoat.

That the wicking in outer layer would just happen to match the shape of the plate is possible, of course, but sounds somewhat unlikely.

04-01-2009 06:01 PM

sailingdog

True, but you haven't sodablasted the hull, so the damage might actually be centered around the two fastener holes.... What is immediately visible is the shape of the block. Also, if the outer layer is matte, which is usually the case, the different directions could be due to the water wicking along the CSM strands.

But if that is the case, I would expect damage to be radiating in circle from the holes, as water wicks pretty much evenly (or perhaps slightly more downward). Instead, it is specifically limited to exactly the area under the ground plate. Since distance from holes to middle of plate (or to vertcal edges) is more than distance to top and bottom edges, if damage would have radiated that way I'd expect the circle of damage to protrude up and down from the holes beyond the immediate ground plate square. It does not. Also there is more damage in some areas farther away from the holes (but still under the ground plate) than it is in their immediate vicinity.

The fact that it is so precisely limited to ground plate shape really seems to invalidate that theory (at least not by itself, may be as a contributing factor).

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